HOSE AS 2093478 - Caterpillar

The SCSA magneto is an ignition system that is capacitor discharged and is electronically controlled. The alternator section of the magneto, which is driven by the engine, has a rotor magnet assembly that is the primary energy source. As the rotor turns, a high and a low voltage is induced in generator coils (L1) and (L3). Two diode bridges (B1) and (B2) rectify the high and low voltages respectively. The high voltage is sent to capacitor (C1) and the low voltage is sent to capacitor (C5). Capacitor (C3) is also charged, but the charge is limited to 20 Volts by zener diode (Z2). The voltage in capacitors (C3) and (C5) direct the flow of current through pulser coil (L4) and potentiometer (P1). This flow of current gives the gate of silicon controlled rectifier (SCR2) a negative signal.As the pulser rotor moves by the pick-up on pulser coil (L4), more voltage is induced which turns on SCR2. As SCR2 is turned on, capacitor (C3) is discharged which turns on SCR1. When SCR1 is turned on, capacitor (C1), discharges its voltage through SCR1 to spark plug transformer (L2). The transformer causes a spark (impulse) of high voltage and low current. This is sent across the electrodes of the spark plug. As the pulser rotor moves by each pulser coil, the same development of spark (impulse) is made.